2) If $L$ is a context free language then $\mathrm{Mirror}(L) = \{ww^r \mid w \in L \}$ is also a context free language?

3) If $L$ is a context free language, then $\mathrm{Sub}(L) = \{x \mid \exists\, y\in\Sigma^*,\; xy\in L\}$ (prefix languages) is also a context free language. ($x$ is prefix of $w$ if there is exists word $y$ such that $xy = w$)